That's a bunch of BS. If you smoke on a regular basis the THC is stored in your fatty tissues and WILL SHOW UP ON A DRUG SCREAN. Just drinking water and green tea is not going to get rid of THC alone. I had a friend that smokes just as much as i do and we smoke like every day at least once a day. He had to take a test to get a new job and he was broke so he failed after he stopped smoking for 30 days. It took his body 60-90 days to get rid of all the THC to leave his body after he quit smoking before he finally passed a test.
This has been my thoughts. THC is stored in the fat cells. (cocaine on the other hand is water soluble. Wasn't drug education wonderful in school? They told us all about all of them, I went down the line, yes, yes, no, yes, no, no.....)
On that, i think your overall level of fitness can make it take longer or less (read:bodyfat level) to cleanse your body of THC.
All the 'drinks' and 'cures' are more of a mask. (kinda like how poppy seeds will make it look like you enjoy heroin. Yes that is true. Ever see a poppy seed roll/bagel in 'county'?)
Now I haven't tried any of these remedies other then stop smoking for a couple months (if I had enough notice) Nor have i poo-poo'd either. (so save the flames)
There are also different tests. The cheapo home style are an easy to beat version. The serious ones (which cost $300-600 us) are nearly impossible to beat (from what I have heard) So be caureful if you plan on 'testing' a method to beat them.